Naslov
Variations of External Shell Morphology within Maastrichtian Praeradiolites Populations and Implications for Generic Taxonomy (the Island of Brač, Adriatic Sea, Croatia)

Autori
Korbar, Tvrtko ; Gušić, Ivan

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Abstracts and Excursion Guidebook of the Sixth International Congress on Rudists / Vlahović, Igor ; Korbar, Tvrtko - Zagreb : Hrvatski geološki institut, 2002, 31-31

ISBN
953-6907-02-X

Skup
Sixth International Congress on Rudists

Mjesto i datum
Rovinj, Hrvatska, 29.09.2002. - 05.10.2002

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
Rudists; Radiolitids; Shell morphology; Taxonomy

Sažetak
Two populations of the genus Praeradiolites DOUVILLÉ (Hippuritacea: Radiolitidae) have been collected from localities situated at the southeastern part of the island of Brač (Adriatic Sea, Croatia). According to the stratigraphic data the sampling localities are situated within the same horizon of the Sumartin Formation, which is attributed to the Lower Maastrichtian. The populations have been analysed both morphometrically and morphologically. A wide range of a morphological variability has been observed within the populations. Furthermore, there is also a variability developed during ontogenesis of some individuals. Several Upper Cretaceous (Turonian to Maastrichtian) “ ; species” ; of the genus belonging to the group of Praeradiolites ponsi have been recognized: Praeradiolites ponsianus (D’ ; ARCHIAC), Praeradiolites toucasi (D’ ; ORBIGNY), Praeradiolites subtoucasi TOUCAS and Praeradiolites boucheroni (BAYLE). However, all these “ ; species” ; have been found within the same Lower Maastrichtian horizon. The morphological variability is the most likely and predominantly a consequence of a phenotypy of the individuals which were probably characterized by the same overall genotype. Thus, the variability is a result of a morphological plasticity of the individuals which belong to the same (morpho)species. Such a plasticity of some radiolitid taxa has been previously reported by many authors. Consequently, there is a need for re-evaluation of the traditional biostratigraphy of the genus, at least for those “ ; species” ; reported from the Adriatic Carbonate Platform. Furthermore, all these “ ; species” ; should be incorporated in a synonymy of a conservative species: Praeradiolites toucasi (D’ ; ORBIGNY), which is the senior synonym. P. toucasi is also characterized by a median value of diagnostic morphological features of the right valve of all the “ ; species” ; . As a result, stratigraphic range of the so defined species is Turonian to Maastrichtian. There are two additional species of the genus (P. anatolicus, P. echennensis) reported from the central and eastern Mediterranean which could also be incorporated into the proposed synonymy. However, the synonymy is not accepted by some recent authors. Conclusively, an additional attention is needed when working on radiolitid (Praeradiolites) taxonomy and, in consequence, biostratigraphy. This research is a contribution to resolving an obviously very problematic taxonomy and biostratigraphy of the Radiolitidae.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

POVEZANOST RADA